Epidemiological estimates indicate that from 5-15 percent of school age children in the United States present with some form of learning disorder (Gearheart, 1981). The term "learning disorder" may be a misnomer in that the specific problems these children experience are not homogeneous, however, as a group they represent an increasingly large proportion of the referrals to pediatric specialists (D'Amato, Dean, and Rattan, 1986). Because "learning disorders" represent a heterogeneous population, problems arise in (1) understanding the elements of an individual child's disorder, (2) communication between professionals, (3) Study of ethological factors, (4) the interface of treatments specific to the child's disorder, and (4) attempts at prevention without an understanding of ethological factors. With the neuropsychological examination offering a picture of the full range of functioning it has been used for sometime with learning disabled children. The use of neuropsychological measures in the subtyping of learning disorders has been attempted by a number of researchers (e.g., Fisk and Rourke, 1979; Petrauskas, & Rourke, 1979). Methodological concerns with these studies involve (1) limited range of neuropsychological measures, (2) samples too small to allow the proper use of multivariate statistics, (3) samples gleaned from neurologic clinics which are not representative of the population, (4) lack of subtype cross validation, (5) failure to consider emotional aspects of childrens' functioning. The proposed research would address subtyping while controlling for these methodological weaknesses. The principle investigator has located a data base of some 1,500 learning disabled children who have been administered the complete Halstead Reitan Neuropsychological Battery (HRNB) over the past 20 years in an Indiana public school district. In Phase One, these archival data will offer the investigators an unprecedented base for subtyping children's learning disorders using multivariate techniques. A sample of 200 learning disabled children to be evaluated in our laboratory will be involved in Phase Two of the investigation. Receiving the full HRNB and Child Behavior Check List, this sample will allow both the cross validation of the subtypes established in Phase One and an examination of the differences between subtypes in emotional functioning.